Corrosion inhibitor composition



Patented Aug. 18, 1953 UNITED TES CORROSION INHIBITOR COMPOSTIION tion of Delaware No Drawing. Application December 30, 1949, Serial No. 136,172

13 Claims. (Cl. 252-855) 1 This invention relates to corrosion inhibiting compositions for use in acid baths employed in metal treatment, particularly for iron and steel. The invention also relates to the acid baths employed for such treatment, containing the corrosion inhibitors of the invention, and to metal treatment processes employing the same.

Metal pickling involves treatment of a metal such as iron or steel with a strong acid bath to remove surface impurities such as oxide scale formed thereon in the course of manufacture. Since the strong acids employed are capable of attacking the metal itself, it is advantageous to add to the bath a corrosion inhibitor which enhances the selective action of the acid on the surface impurities, and substantially reduces or prevents attack of the metal by the acid.

Another field of metal treatment employing strong aqueous acids is in acidizing treatment of oil wells. introduced into the oil Well to increase the flow of oil by attacking the underground porous rock formations containing the oil. Since the acid solutions come in contact with metal equipment of the well, it is advantageous to incorporate a corrosion inhibitor in the acid solution to prevent excessive damage of the metal equipment.

Another problem arising in acidizing treatment of oil wells lies in the resolution or inhibition of oil-in-water emulsions which normally tend to form during and as a result of the acidizing treatment. For this purpose, numerous surfaceactive agents have been suggested for incorporation in the well treating fluid. For example, it has been suggested in USP 2,233,383 to employ water-soluble non-ionic surface-active polyglycol ethers, prepared by reaction of ethylene oxide on a water-insoluble acyclic alcohol, as an emulsion breaker in the acidizing of oil wells. As indicated in this patent, prevention of corrosion of the metal equipment by the acids employed calls for the additional use of a corrosion inhibitor.

Higher primary aliphatic and alicyclic amines, especially monoamines, which are at most slightly soluble in water, and particularly those containing 12 to 20 carbon atoms, have some corrosion inhibiting action in acid solutions, but are generally only partially effective to prevent substantial corrosion when employed in the low concentrations (of the order of 0.01 to 0.20%) in which they can be incorporated in acid solutions with satisfactory economy and without substantial separation of solids.

We have discovered that mixtures of higher primary aliphatic or alicyclic amines with water- A strong aqueous mineral acid is soluble non-ionic emulsifying agents of the type containing a polyalkylene glycol ether radical of at least 4 oxyalkylene radicals, attached by an ether or carboxy ester linkage to a higher aliphatic, alicyclic or alkylated aromatic hydrocarbon radical of at least 12 (e. g. 12 to 24 carbon atoms), and wherein the weight ratio of said amine to said emulsifying agent is substantially within the range 1:9 to 1:1, and preferably about 1:3, are highly effective corrosion inhibitors for ferrous metals such as iron and steel, unexpectedl exceeding the inhibiting effect of their respective components when used in strong acid solutions (e. g. solutions of a pH less than 2) in concentrations of the order of 0.01 to 0.20%.

The corrosion inhibitor compositions of this invention are soluble or readily dispersible in strong aqueous acid solutions, and can be readily compounded to avoid undesirable separation of solids from the solution during use in metal treatment.

The corrosion inhibiting mixtures of this invention are highly effective in the acid baths employed for pickling which contain, for example,

' sulfuric, hydrochloric, nitric, hydrofluoric, phosphoric, formic or acetic acid in concentrations of about 5 to 15%, or in equivalent aqueous solutions of acid salts such as sodium bisulfate. They are also effective and useful as corrosion inhibitors in the acidizing of oil wells with strong acids (e. g. hydrochloric or hydrofluoric acid) of 5 to 20% concentration, wherein the corrosion inhibiting compositions also act to prevent or inhibit formation, and to resolve, water-in-oil emulsions.

As indicated above, the amines employed in the compositions of this invention are aliphatic and alicyclic primary monoamines of 12 to 20 carbon atoms, particularly the primary amines derived from fatty acids of natural fats by replacement of the carboxyl group with an amino or an amino methyl group, and the alicyclic primary monoamines derived from rosin or its hydrogenated or dehydrogenated derivatives, e. g. by replacing carboxyl groups with an amino methyl group in abietic or hydrogenated or dehydrogenated abietic acid, or by introducing a primary amino group into the nucleus of abietyl compounds and their hydrogenated or dehydrogenated derivatives, e. g. by nitration and reduction as disclosed in USP 2,367,001, or by halogenation and amination as disclosed in USP 2,240,936.

The non-ionic emulsifying agents employed in the corrosion inhibitor compositions of this invention are water-soluble or colloidally soluble polyglycol ethers and esters of higher fatty or alicyclic alcohols or carboxy acids, and of alkylphenols, of the order of 12 to 2& carbon atoms, which are produced by condensation of such acids, phenols or alcohols with at least 4 molecular equivalents of ethylene oxide or a closely analogous alkylene oxide such as propylene oxide. Preparation of such compounds is disclosed, for example in USP 1,970,518.

The following compositions, prepared in each case by thoroughly mixing the ingredients here given, and warming until a homogeneous mix.- ture was obtained, illustrate a number of representative corrosion inhibiting compositions in accordance with our invention. Parts are by weight.

Talloil is a byproduct of the sulfate process for making wood pulp, thecrude product usually consisti ng of rosin acids (30 to 65%) and fatty acids (are 60%) and the refined product containing, for example 35 to 40% of rosin acids and 50 to ar higher fatty acids together w t up to time 10% iinsaponifiable ingredients.

" The polyethoxylated derivatives employed in the foregoing colrnpositip fls contain 1 or more, and particularl from 8 to 15 ethenoxy radicals, and are prepared by condensing ethylene oxide in the appropriate molecular proportions with talloil ti wit h the di isoamylphenol. Similar .e hpf i h a e eht hed b ri g e m l t yi ie we d ri a ve new; Phe o r e .e .die when ede o l eh 0 e e of h e xid w th e e hee ve tal il- ?ie'hye eele tin l ih he is e m ry 'ih .e r ve't e ef sieh dree ie e .ee in which th whee reen i it ple d y t. -NH. ere I he l ewihe tab e. t 39" 'ee ee e m Th stra ht-9. am el hetie .ehl he th oresome l m'eoe t hsf.ele ired rehl natu al fe fe t' a ids t 18 e -bee te he. is pr par d fcrexample, by amination of the fatty alcohol m hh re Detainee b reduet eh e eeter 9 fatty a id r h etel tie h dreeehe ie e the we ehehd e h l ee- The err'e ieh i ibit n i'fecl e the l reeeihe compositions, and also of the respective compoh hts of aid e mnee ehs w s t ed by 11. n e he the inhib ti compo it ohs and the r Spec-tire dient alon c cent ations .e 0.01, 0.10 and 0.20%, in 15% aqueous hydroh o i at end terminin th les i w i du in m nutes mmer en in th resulting Solutions, of approximately equal-sized samples of Tinch hot rolled steel sheets, and comparing the per cent loss in weight with the corresponding loss of a similar sample in hydroc c e of h s me temperatur end centration and in the absence of any inhibitor. The loss in weight of the latter blank deter at e emo tee to Inhibiting efficiency was calculated percent- 4 age as the quotient of the difference in loss in weight between the sample with the inhibitor and without the inhibitor, over the loss in weight in the absence of an inhibitor.

fhe results of the tests were as follows:

$imi'lar inhibitor efliciencies were obtained with corresponding -mixtures of polyethoxylated nonyl phenol or ethoxylated talloil contain-mg about 50-molecular equivalents of ethylene oxide with the rosin amine 01' the fatty amine mixture.

As indicated in the :foregoing table, the cor'rosien inhibiting effector mixtures of the *higher fatty and alicyclic amines with-polyalkylene' glycol esters and ethers substantially exceeds the corrosion inhibiting effect of either of the ingredients when used in corresponding concentrations alone. In the instance of rosin amine, which attained 08% efficiency at 0.2% concentration when used alone, the insolubility of the material at this concentration, and the resulting separation of solids, would render its use impractical for commercial application. However, mixtures containing 50% or more of the polyglycol ethers or esters with the insoluble amines yield stable dispersions or solutions in the strong acid medium employed, and are satisfactory for use in metal pickling baths or in-aciclizing oil wells.

As set out above, the amines employed accordance with this invention are substantially water-insoluble (i. e., water-insoluble or at most, slightly water-soluble) higher primary'aliphatic and alic-yclic monoamines, especially those containing about 12 to 20 carbon atoms, such as priamine? e erive m the fatty e id of naturalfats, from the carboxy acids of rosin, e. g. abietic acid and its hydrogenated and dehydrogenated derivatives, and the like. The polyai-ke yletee .eerhh hee mhle d i the r e iting compositions are those derived from the fatty eeie e 9 heth iet o m t o he .eleehele. I em e et acid and p genated or dehydrogenated derivatives or resin. e fr leehe e .eere spe he h h tte eempeuh e. and ree e h p e l of at l s 1.2 and pre bl 1. t 2% Ieer er The ber of ZI1 9f eth lene er h pyiehe id eheed w h these mater als te P u e h pelyelheryleted e hlheu ds should b at least 4 t m e e tisf tery u eeev The l mit of h m e u e p eren Q el yleh e iee hu cond n ed i 5 1 thet the pro ebe emain eel-leifil ll e e In gen u to 6 mole 9 ethy e pXide has be n iodii Suita le baths, while with lower proportions of amine, the corrosion inhibiting effect decreases excessively.

The compositions are suitably employed in strong acid baths used for metal pickling or oil well treatment most advantageously and economically in concentrations of 0.01 to 0.2%. The baths may contain 5 to 20% of a mineral acid such as HCl, H2804, HzFz, H3PO4, HNO3, or in some cases, organic acids such as formic or acetic acid. Such baths have a pH of less than 2 and generally less than 1. In pickling operations, elevated temperatures of the order of 80 0., e. g. 50 to 100 C., are employed, and the bath is preferably maintained in motion relative to the metal articles to be treated. In the acidizing of oil wells, mineral acids, especially hydrochloric or hydrofluoric acid are used in concentrations of 5 to 20%, and the solution is not heated, but is introduced at ambient temperature into the oil well. When employed in the oil well treating solutions, the corrosion inhibiting compositions of the invention not only inhibit corrosion of the metal equipment, but also inhibit formation of water-in-oil emulsions.

Variations and modifications which will be obvious to those skilled in the art can be made in the foregoing compositions and procedure without departing from the nature or scope of the invention.

We claim:

1. A corrosion inhibiting composition for use in the treatment of metals with acid baths, which consists essentially of a substantially water-insoluble primary amine of the class consisting of aliphatic and alicyclic monoamines of 12 to 20 carbon atoms, and a non-ionic dispersing agent of the class consisting of the polyalkoxylated derivatives of aliphatic and alicyclic monocarboxy acids, of aliphatic and alicyclic monohydric alcohols and of alkylphenols, said acids, alcohols and alkylphenols having 12 to 24 carbon atoms, said derivatives thereof containing at least 4 oxyalkylene radicals and said oxyalkylene radicals each containing 2 to 3 carbon atoms, the weight ratio of said amine to said dispersing agent being substantially within the range of 1:1 to 1:9.

2. A corrosion inhibiting composition as defined in claim 1, wherein the dispersing agent is polyethoxylated talloil.

3. A corrosion inhibiting composition as defined in claim 1, wherein the dispersing agent is a polyethoxylated alkylphenol.

4. A corrosion inhibiting composition as defined in claim 1, wherein the amine is a dehydroabietinyl amine.

5. A corrosion inhibiting composition as defined in claim 1, wherein the amine is a higher fatty amine corresponding to a natural fat fatty acid.

6. A corrosion inhibiting composition essentially consisting of dehydroabietinyl amine and polyethoxylated talloil, wherein the weight ratio of said amine to said talloil derivative is about 1:3.

7. A corrosion inhibiting composition consisting of polyethoxylated di-isoamylphenol and dehydroabietinyl amine, wherein the weight ratio of said amine to said phenol derivative is about 1:3.

8. A corrosion inhibiting composition consisting essentially of a mixture of straight-chain aliphatic primary monoamines of 14 to 18 carbon atoms and of a polyethoxylated talloil, wherein the weight ratio of said amine mixture to said talloil derivative is about 1 :3.

9. An acid treatment bath for metals, having a pH of less than 2 and containing from 0.01 to 0.2% of a corrosion inhibiting composition as defined in claim 1.

10. An acid treatment bath for metals, containing 5 to 20% of a mineral acid and from 0.01 to 0.2% of a corrosion inhibiting composition as defined in claim 1.

11. An acid treatment bath for metals, containing about 15% hydrochloric acid and from 0.01 to 0.2% of a corrosion inhibiting composition as defined in claim 1.

12. A process for pickling iron and steel, which comprises immersing the metal in an acid bath having a pH less than 2 and containing from 0.01 to 0.2% of a corrosion inhibiting composition as defined in claim 1.

13. A process for the treatment of oil Wells having ferrous metal equipment therein, which comprises introducing into the well an acid bath containing 5 to 20% of a mineral acid and from 0.01 to 0.2% of a corrosion inhibiting composition as defined in claim 1, wherein said ferrous 11:13:51 equipment is exposed to contact with said ROBERT L. SUNDBERG. CHARLES P. ALBUS. JAMES M. CROSS.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,970,578 Schoeller et al. Aug. 21, 1934 2,233,383 De Groote et al. Feb. 25, 1941 2,246,842 De Groote et al. June 24, 1941 2,367,001 Campbell Jan. 9, 1945 2,510,063 Bried June 6, 1950 

1. A CORROSION INHIBITING COMPOSITION FOR USE IN THE TREATMENT OF METALS WITH ACID BATHS, WHICH CONSISTS ESSENTIALLY OF A SUBSTANTIALLY WATER-INSOLUBLE PRIMARY AMINE OF THE CLASS CONSISTING OF ALIPHATIC AND ALICYCLIC MONOAMINES OF 12 TO 20 CARBON ATOMS, AND A NON-IONIC DISPERSING AGENT OF THE CLASS CONSISTING OF THE POLYALKOXYLATED DERIVATIVES OF ALIPHATIC AND ALICYCLIC MONOCARBOXY ACIDS, OF ALIPHATIC AND ALICYCLIC MONOHYDRIC ALCOHOLS AND OF ALKYLPHENOLS, SAID ACIDS, ALCOHOLS AND ALKYLPHENOLS HAVING 12 TO 24 CARBON ATOMS, SAID DERIVATIVES THEREOF CONTAINING AT LEAST 4 OXYALKYLENE RADICALS AND SAID OXYALKYLENE RADICALS EACH CONTAINING 2 TO 3 CARBON ATOMS, THE WEIGHT RATIO OF SAID AMINE TO SAID DISPERSING AGENT BEING SUBSTANTIALLY WITHIN THE RANGE OF 1:1 TO 1:9. 